The format is a character string which contains three
types of objects:

Plain characters, which are simply copied to standard output,

Character escape sequences, which are converted and copied to standard output,

Format specifications, each of which causes printing of the next successive
argument.

The format is reused as necessary to consume all of the arguments. If the format requires more arguments than are supplied, the extra format specifications behave as if a zero value or null string, as appropriate, had been supplied.